1. Field of the Invention
The present invention relates to a magnetic recording/reproduction apparatus.
2. Description of the Related Art
An example of conventional magnetic recording/reproduction apparatus is disclosed in Japanese Laid-Open Utility Model Publication No. 61-195552. Referring to FIG. 37, the conventional magnetic recording/reproduction apparatus will be described.
A conventional magnetic recording/reproduction apparatus 300 includes a typical tape path where a tape 316 is drawn out from a tape cassette 310 and passes around a rotary head cylinder 318 for recording and reproduction.
The tape 316 is driven by rotating a capstan 320 with a capstan motor 323 while a pinch roller 319 is pressed against the capstan 320. The rotation of the capstan motor 323 is also transmitted to a fixed gear 332 and a swing gear 334 via gears 324 and 325 and a timing belt 326, and then transmitted selectively to a driving gear 328 of an S reel base 301 or a driving gear 329 of a T reel base 302.
The swing gear 334 is swingably attached to a shaft 339 extending from a swing plate 333, which is in turn swingably attached to a shaft of the fixed gear 332.
In the conventional magnetic recording/reproduction apparatus having the above configuration, when the tape is to be sent forward (e.g., when recorded images are to be reproduced, the tape is to be fast-forwarded, etc.), the apparatus works as follows. The capstan motor 323 is rotated forward (counterclockwise (CCW)), rotating the capstan 320 forward. This allows the tape 316 to be sent forward. At the same time, the rotation of the capstan 320 is transmitted to the fixed gear 332 via the timing belt 326, which causes the swing plate 333 to swing clockwise (CW) around a shaft 331 and thus the swing gear 334 to engage with the driving gear 329 of the T reel base 302. The T reel base 302 then rotates clockwise, thereby allowing the tape 316 to be wound onto a winding reel inside the tape cassette 310.
In reverse, when the tape is to be sent backward (e.g., when recorded images are to be reproduced in reverse, the tape is to be rewound, etc.), the apparatus works as follows. The capstan motor 323 is rotated backward (clockwise), rotating the capstan 320 backward. This allows the tape 316 to be sent backward. At the same time, the rotation of the capstan 320 is transmitted to the fixed gear 332 via the timing belt 326, which causes the swing plate 333 to swing counterclockwise around the shaft 331 and thus the swing gear 334 to engage with the driving gear 328 of the S reel base 301. The S reel base 301 then rotates counterclockwise thereby allowing the tape 316 to be wound onto a supply reel inside the tape cassette 310.
In the above conventional configuration, a problem arises when it is attempted to shift the mode from a mode in which the tape is sent forward (e.g., a reproduction mode) to a mode in which the tape is sent backward (e.g., a reverse reproduction mode). That is, when the direction of the rotation of the capstan 320 is reversed from counterclockwise to clockwise while the pinch roller 319 being kept pressed against the capstan 320, the portion of the tape 316 located at the capstan 320 immediately starts to be sent backward. On the contrary, in order to complete the mode shift, the swing gear 334 must move from the position at which it is engaged with the driving gear 329 of the T reel base 302 (shown by the solid lines in FIG. 37) to the position at which it is engaged with the driving gear 328 of the S reel base 301 (shown by the one-dot chain lines in FIG. 37). Accordingly, a certain time lag arises from the start of the backward rotation of the capstan 320 until the S reel base 301 starts winding the tape 316, causing slacking of the tape 316 in the tape path.
During the above time lag, the tape 316 passes around the rotary head cylinder 318 at a tension lower than a normal tension. At such a low tension, it is impossible for a head mounted on the rotary head cylinder 318 to effect magnetic recording/reproduction, resulting in failure in displaying reversely reproduced images. Moreover, when the tape slacking is great, the tape 316 tends to be displaced from posts 317A and 317B which guide the tape 316. If the tape 316 continues to run in the displaced state, the tape 316 will be greatly damaged. This problem also applies to the case of the mode shift from the mode in which the tape is sent backward to the mode in which the tape is sent forward.
The object of the present invention is to provide a highly reliable mechanism in which the mode shift is effected without causing slacking of a tape when the mode is shifted from a forward mode to a backward mode or vice versa, so as to be free from discontinuity of images and damaging of the tape.